Array substrate and manufacturing method thereof

ABSTRACT

A manufacturing method of an array substrate includes the steps of providing a base plate and forming a thin-film transistor (TFT) layer on the base plate; forming a quantum dot layer on the TFT layer; and forming a protective filter layer on the quantum dot layer to provide protection to the quantum dot layer. The protective filter layer also provides an effect of light filtering in order to prevent ultraviolet light or blue light from transmitting therethrough.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of co-pending U.S. patent applicationSer. No. 14/914,619, which is a national stage of PCT Application No.PCT/CN2015/098341, filed on Dec. 22, 2015, claiming foreign priority ofChinese Patent Application No. 201510618853.6, filed on Sep. 24, 2015.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the field of display technology, and inparticular to an array substrate and a manufacturing method thereof.

2. The Related Arts

Liquid crystal displays (LCDs) have a variety of advantages, such asthin device body, low power consumption, and being free of radiation,and are thus widely used in for example liquid crystal televisions,mobile phones, personal digital assistants (PDAs), digital cameras,computer monitors, and notebook computer screens. The liquid crystaldisplay generally comprises an enclosure, a liquid crystal display panelarranged in the enclosure, and a backlight module mounted in theenclosure. The structure of the liquid crystal display panel isgenerally made up of a thin-film transistor (TFT) array substrate, acolor filter (CF) substrate, and a liquid crystal layer between the twosubstrates and the operation principle is that a drive voltage isapplied to the two glass substrates to control liquid crystal moleculesof the liquid crystal layer to rotate in order to refract out light froma backlight module to generate an image.

Quantum dots are nanometer semiconductor crystals having a radiussmaller than or close to Bohr radius and most are three-dimensionalnanometer materials composed of elements of II-VI group or III-V group.Due to the quantum confinement effect, the transportation of electronsand holes in the quantum dots is constrained so as to change thecontinuous energy band into discrete energy levels. When the size of thequantum dot differs, the quantum confinement effect exhibits onelectrons and holes is different, making the structure of discreteenergy levels different. When excited by an external energy, quantumdots of different sizes give off light of different wavelengths, namelydifferent colors of light. The advantages of quantum dot are that byadjusting the size of the quantum dot, it is possible to provide a rangeof wavelength of light emission that covers the infrared light and theentire visible light band and the waveband of the emission light isnarrow with high degree of color saturation. The quantum dot materialshows a high quantum conversion efficiency and the property of thematerial is stable. The manufacturing process and simple and diverse,allowing manufacturing thereof from solutions, of which the resourcesare rich. The quantum dot may absorb blue light that has a relativelyshort wavelength and, after being excited, exhibits a light color of arelatively long waveband. Such characteristics make the quantum dotcapable of changing the color the light emitting from a backlightsource.

A conventional liquid crystal display panel relies on color filteringachieved with an arrangement of color filter layers, such as a redfilter layer, a green filter layer, and a blue filter layer, therein inorder to convert white light emitting from a light source intomonochromic light, such as red, green, and blue. The color filter layersof different colors allow light of different wavebands to pass so as toachieve colorful displaying of a liquid crystal display panel. With theadvance of science and technology, people desire continuous improvementof color saturation and gamut for the liquid crystal display panel. Toexpand the color gamut range of a liquid crystal display panel requiresincreasing the color purity of the color filter layers and this in turnrequires the content of pigment to be increased. This, however, lowersdown light transmission rate of the color filter layer. Further, tomaintain the display brightness of the liquid crystal display panel, italso needs to increase the intensity of emission light of the lightsource and this would lead to increased power consumption of the liquidcrystal display panel.

The quantum dot technology brings total upgrading in all sectors, suchas color gamut coverage, preciseness of color control, color purity ofred, green, and blue colors and realizes, in an evolutionary way, fullcolor displaying, providing the most realistic way of restoration ofgenuine color of an image, and is thus considered the world-wide highspot of display techniques and affecting the global revolution ofdisplay technology. The conventional quantum dot display technology isachieved by directly introducing quantum dots into between twosubstrates (a liquid crystal cell) of a liquid crystal display panel inorder to supplement the insufficiency of color displaying with the colorfilter layers and to expand the range of displayed color gamut. However,the conventional manufacturing operations of the liquid crystal displaypanels constrain the exploitation of quantum dot performance. It is aissue to be studies for further improving the stability of quantum dots.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an array substrate,wherein a quantum dot layer and a protective filter layer are providedon the array substrate to compensate the insufficiency of colordisplaying of an existing color filter layer, expand the range of colorgamut, and also overcome the issues of poor performance and stability ofthe prior art quantum dots.

Another object of the present invention is to provide a manufacturingmethod of an array substrate, wherein the method allows for easy andsimple formation of a quantum dot layer and a protective filter layer onan array substrate to compensate the insufficiency of color displayingof an existing color filter layer, expand the range of color gamut, andalso overcome the issues of poor performance and stability of the priorart quantum dots.

To achieve the above objects, the present invention provides an arraysubstrate, which comprises: a base plate, a TFT layer arranged on thebase plate, a quantum dot layer arranged on the TFT layer, and aprotective filter layer arranged on the quantum dot layer;

the protective filter layer forming dense protection to the quantum dotlayer, the protective filter layer providing an effect of lightfiltering, the protective filter layer filtering ultraviolet light orblue light within a predetermined waveband.

The quantum dot layer contains therein quantum dots that comprisesnanometer particles formed of one or multiple of semiconductorscomprising elements of IIB-VIA group, semiconductors comprising elementsof IIIA-VA group, and carbon quantum dot, the quantum dots having astable diameter of 0-20 nm.

The quantum dot layer emits light having a color of red, green, blue,yellow, and purple or a combination of multiple ones thereof.

The protective filter layer is formed of a material comprising one ofsilicon nitride, silicon oxide, indium tin oxide, polyimide, andpolyfluorene derivatives.

The protective filter layer comprises a color filter layer formedthereon.

The present invention also provides an array substrate manufacturingmethod, which comprises the following steps:

(1) providing a base plate and forming a TFT layer on the base plate;

(2) forming a quantum dot layer on the TFT layer; and

(3) forming a protective filter layer on the quantum dot layer.

Step 2 is specifically performed by applying a vapor deposition processto form a quantum dot film on the TFT layer so as to form the quantumdot layer.

Step 2 is specifically performed by providing a quantum dot material anda dissolving medium, dissolving and dispersing the quantum dot materialin the dissolving medium and uniformly mixed to form a quantum dotpaste, and applying the quantum dot paste to form a film on the TFTlayer and drying and curing to obtain the quantum dot layer.

In Step 2, the quantum dot material is oil soluble or water soluble; thequantum dots are in the form of spheres, bars, or fibrous forms; thedissolving medium is silica series or epoxy series; and in Step 2 thequantum dot paste is applied to the TFT layer to form the film by meansof spray coating, spin coating, printing, or slot-die coating.

The array substrate manufacturing method further comprises:

(4) forming a color filter layer on the protective layer.

The present invention further provides an array substrate, whichcomprises: a base plate, a TFT layer arranged on the base plate, aquantum dot layer arranged on the TFT layer, and a protective filterlayer arranged on the quantum dot layer;

the protective filter layer forming dense protection to the quantum dotlayer, the protective filter layer providing an effect of lightfiltering, the protective filter layer filtering ultraviolet light orblue light within a predetermined waveband;

wherein the quantum dot layer contains therein quantum dots thatcomprises nanometer particles formed of one or multiple ofsemiconductors comprising elements of IIB-VIA group, semiconductorscomprising elements of IIIA-VA group, and carbon quantum dot, thequantum dots having a stable diameter of 0-20 nm;

wherein the quantum dot layer emits light having a color of red, green,blue, yellow, and purple or a combination of multiple ones thereof; and

wherein the protective filter layer is formed of a material comprisingone of silicon nitride, silicon oxide, indium tin oxide, polyimide, andpolyfluorene derivatives.

The efficacy of the present invention is that the present inventionprovides an array substrate. The array substrate comprises a quantum dotlayer, and a protective filter layer is formed on the quantum dot layer.The quantum dot layer helps improve color saturation and color purityand expands the range of color gamut. The protective filter layerprovide dense protection to the quantum dot layer to prevent damagesinduced on the quantum dot layer by subsequent manufacturing processesand also prevents impurities contained in the quantum dot paste fromentering the liquid crystal layer to affect the performance ofdisplaying. Further, the protective filter layer provides an effect oflight filtering and may prevent a portion of UV backlighting or laserbacklighting, which remains after the backlighting has been used toexcite the quantum dots, from transmitting therethrough so as to improvethe efficiency and stability of the quantum dot layer. The presentinvention also provides an array substrate manufacturing method. Themethod can be easily carried out and forms a quantum dot layer on anarray substrate to supplement the insufficiency of color displaying of aconventional color filter layer and expand the range of color gamut. Byforming a protective filter layer on the quantum dot layer, theefficiency and stability of the quantum dot layer can be improved.

For better understanding of the features and technical contents of thepresent invention, reference will be made to the following detaileddescription of the present invention and the attached drawings. However,the drawings are provided for the purposes of reference and illustrationand are not intended to impose limitations to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution, as well as other beneficial advantages, of thepresent invention will become apparent from the following detaileddescription of an embodiment of the present invention, with reference tothe attached drawings.

In the drawings:

FIG. 1 is a schematic view illustrating the structure of a firstembodiment of an array substrate according to the present invention;

FIG. 2 is a schematic view illustrating the structure of a display panelthat includes the array substrate illustrated in FIG. 1;

FIG. 3 is a schematic view illustrating the structure of a secondembodiment of the array substrate according to the present invention;

FIG. 4 is a schematic view illustrating the structure of a display panelthat includes the array substrate illustrated in FIG. 3;

FIG. 5 shows a plot of transmission spectrum of a polyimide materialfilm; and

FIG. 6 is a flow chart illustrating a manufacturing method of the arraysubstrate according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To further expound the technical solution adopted in the presentinvention and the advantages thereof, a detailed description is given toa preferred embodiment of the present invention and the attacheddrawings.

Referring to FIG. 1, firstly, the present invention provides an arraysubstrate, which comprises: a base plate 1, a thin-film transistor (TFT)layer 2 arranged on the base plate 1, a quantum dot layer 3 arranged onthe TFT layer 2, and a protective filter layer 4 arranged on the quantumdot layer 3.

Specifically, the quantum dot layer 3 contains quantum dots that arenanometer particles having a stable diameter of 0-20 nm formed of one ormultiple of semiconductors comprising elements of IIB-VIA group (such ascadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride(CdTe), and zinc selenide (ZnSe)), semiconductors comprising elements ofIIIA-VA group (such as indium phosphide (InP), and indium assenide(InAs)), and other quantum dot materials, such as carbon quantum dot.

Specifically, emission light colors of the quantum dot layer 3 include,but not limited to, one of red, green, blue, yellow, and purple or acombination of multiple ones thereof. The quantum dot layer 3 can be afilm layer formed on an entire surface by means of a monocolor quantumdot or mixed multicolor quantum dots, or can alternatively be a filmlayer involving a pixel pattern by subjecting monocolor quantum dots ormulticolor quantum dots to a patterning operation. Specifically, theprotective filter layer 4 is formed of a material that is selected frominorganic materials, such as silicon nitride (SiNx), silicon oxide(SiO2), indium tin oxide (ITO), or organic materials, such as polyimide(PI) and polyfluorene (PFN) derivatives. These materials exhibit aneffect of light filtering and may cut off ultraviolet light (UV) or bluelight having a short wavelength and provide an excellent effectfiltering for the ultraviolet light or blue light of short wavelengths,and exhibit an excellent effect of transmission for visible light havinga relatively long wavelength and allows for improvement of filteringeffect by adjusting molecular structures thereof. As shown in FIG. 5, apolyimide film shows a high transmission rate for light of wavelength of380-780 nm and has an abruptly lowered transmission rate for shortwavelength light having a wavelength less than 380 nm to thus provide anexcellent effect of filtering for ultraviolet light having a shortwavelength.

The protective filter layer 4 provides dense protection to the quantumdot layer 3 to prevent damages induced on the quantum dot layer 3 bysubsequent manufacturing processes (such as development operation andwater washing operation of the color filter layer) and also to preventimpurities contained in the quantum dot paste from entering the liquidcrystal layer to affect the performance of displaying. Further, theprotective filter layer 4 also provides an effect of light filtering andmay prevent a portion of UV backlighting or laser backlighting, whichremains after the backlighting has been used to excite the quantum dots,from transmitting out. Taking a quantum dot layer 3 of which the colorof emission light is red or green and the backlighting emitting from abacklight module being blue light as an example, the arrangement of theprotective filter layer 4 can be used to filter off blue light toprevent a remaining portion the blue light that has not been put intoeffect in exciting the quantum dot layer 3 from transmitting through theprotective filter layer 4 after the blue light has been applied forexcitement purpose, so as to increase the emission efficiency of thequantum dot layer 3, while the protective filter layer 4 allows red orgreen light to transmit therethrough for color displaying.

Referring to FIGS. 2 and 4, the array substrate is laminated with apackage lid to form a display panel. The display panel can be a COA(Color Filter On Array) panel or a non-COA panel. Further, the presentinvention imposes no limitations to the driving mode applicable to thedisplay panel and is equally applicable to various modes, includingin-plane switching (IPS), twisted nematic (TN), vertical alignment (VA),organic light emitting diode (OLED), and quantum dot LED (QLED).

As shown in FIG. 2, the display panel illustrated in a non-COA panel,wherein a color filter layer 5 is arranged on a base plate 6 of apackage lid.

In addition, referring to FIG. 3 in combination with FIG. 4, FIG. 4illustrates a display panel that is a COA panel and a color filter layer5 is arranged on a protective filter layer 4 of an array substrate.

Referring to FIG. 6, in combination with FIG. 1, the present inventionalso provides an array substrate manufacturing method, which comprisesthe following steps:

Step 1: providing abase plate 1 and forming a TFT layer 2 on the baseplate 1.

Specifically, the base plate 1 is a transparent plate, preferably aglass plate. The TFT layer 2 comprises a plurality of TFT units arrangedin an array and pixel electrodes connected to the TFT units.

Step 2: forming a quantum dot layer 3 on the TFT layer 2.

Specifically, in Step 2, a quantum dot material and a dissolving mediumare provided. The quantum dot material is dissolved and dispersed in thedissolving medium and is uniformly mixed to form a quantum dot paste.The quantum dot paste is then applied to form a film on the TFT layer 2and is then dried and cured to form the quantum dot layer 3.

In Step 2, the quantum dot material provided may be obtained byapplication of one of various non-limiting processes, such as surfacegrafting or surface coating, for modifying the quantum dot, in order tomake it compatible with the dissolving medium and being oil soluble orwater soluble. The quantum dots of the quantum dot material can be ofany suitable shape, such as sphere, bar, or a fibrous form. Thedissolving medium can be silica series or epoxy series dissolving mediumsystems and may be specifically selected according to multiple factors,including light emission characteristics and dissolving behavior of thequantum dots and the percentages of the ingredient components and themixture ratio thereof with respect to the quantum dots can be adjustedaccording to the desired result of mixture in order to provide anoptimum result of mixture. The process that the quantum dot paste isapplied to form a film on the TFT layer 2 in Step 2 includes spraycoating, spin coating, printing, and slot-die coating.

Or alternatively, in Step 2, the quantum dot layer 3 can be a layer ofquantum dot film formed on the TFT layer 2 through vapor deposition.

The quantum dot layer 3 can be a film layer formed on an entire surfaceby means of a monocolor quantum dot or mixed multicolor quantum dots, orcan alternatively be a film layer involving a pixel pattern bysubjecting monocolor quantum dots or multicolor quantum dots to apatterning operation. If the quantum dot layer 3 is a patterned filmlayer, then a corresponding patterning operation must be included inStep 2.

Step 3: forming a protective filter layer 4 on the quantum dot layer 3.

Specifically, the protective filter layer 4 is formed of a material thatis selected from inorganic materials, such as silicon nitride (SiNx),silicon oxide (SiO2), indium tin oxide (ITO), or organic materials, suchas polyimide (PI) and polyfluorene (PFN) derivatives. These materialsexhibit an effect of light filtering and may cut off ultraviolet light(UV) or blue light having a short wavelength and provide an excellenteffect filtering for the ultraviolet light or blue light of shortwavelengths, and exhibit an excellent effect of transmission for visiblelight having a relatively long wavelength and allows for improvement offiltering effect by adjusting molecular structures thereof. As shown inFIG. 5, a polyimide film shows a high transmission rate for light ofwavelength of 380-780 nm and has an abruptly lowered transmission ratefor short wavelength light having a wavelength less than 380 nm to thusprovide an excellent effect of filtering for ultraviolet light having ashort wavelength.

The protective filter layer 4 provides dense protection to the quantumdot layer 3 to prevent damages induced on the quantum dot layer 3 bysubsequent manufacturing process (such as development operation andwater washing operation of the color filter layer) and also to preventimpurities contained in the quantum dot paste from entering the liquidcrystal to affect the performance of displaying. Further, the protectivefilter layer 4 also provides an effect of light filtering and mayprevent a portion of UV backlighting or laser backlighting, whichremains after the backlighting has been used to excite the quantum dots,from transmitting out. Taking a quantum dot layer 3 of which the colorof emission light is red or green and the backlighting emitting from abacklight module being blue light as an example, the arrangement of theprotective filter layer 4 can be used to filter off blue light toprevent a remaining portion the blue light that has not been put intoeffect in exciting the quantum dot layer 3 from transmitting through theprotective filter layer 4 after the blue light has been applied forexcitement purpose, so as to increase the emission efficiency of thequantum dot layer 3, while the protective filter layer 4 allows red orgreen light to transmit therethrough for color displaying.

Further, the array substrate can be a COA array substrate, and in thiscase, the array substrate manufacturing method further comprises: Step4, in which a color filter layer 5 is formed on the protective layer 4.

In summary, the present invention provides an array substrate. The arraysubstrate comprises a quantum dot layer, and a protective filter layeris formed on the quantum dot layer. The quantum dot layer helps improvecolor saturation and color purity and expands the range of color gamut.The protective filter layer provide dense protection to the quantum dotlayer to prevent damages induced on the quantum dot layer by subsequentmanufacturing processes and also prevents impurities contained in thequantum dot paste from entering the liquid crystal layer to affect theperformance of displaying. Further, the protective filter layer providesan effect of light filtering and may prevent a portion of UVbacklighting or laser backlighting, which remains after the backlightinghas been used to excite the quantum dots, from transmitting therethroughso as to improve the efficiency and stability of the quantum dot layer.The present invention also provides an array substrate manufacturingmethod. The method can be easily carried out and forms a quantum dotlayer on an array substrate to supplement the insufficiency of colordisplaying of a conventional color filter layer and expand the range ofcolor gamut. By forming a protective filter layer on the quantum dotlayer, the efficiency and stability of the quantum dot layer can beimproved.

Based on the description given above, those having ordinary skills ofthe art may easily contemplate various changes and modifications of thetechnical solution and technical ideas of the present invention and allthese changes and modifications are considered within the protectionscope of right for the present invention.

What is claimed is:
 1. An array substrate manufacturing method,comprising the following steps: (1) providing a base plate and forming athin-film transistor (TFT) layer on the base plate; (2) forming aquantum dot layer on the TFT layer; and (3) forming a protective filterlayer on the quantum dot layer, wherein the protective filter layerprovides an effect of light filtering so as to prevent ultraviolet lightor blue light within a predetermined waveband from transmittingtherethrough, and further comprising the following step: (4) forming acolor filter layer on the protective layer.
 2. The array substratemanufacturing method as claimed in claim 1, wherein Step 2 isspecifically performed by applying a vapor deposition process to form aquantum dot film on the TFT layer so as to form the quantum dot layer.3. The array substrate manufacturing method as claimed in claim 1,wherein Step 2 is specifically performed by providing a quantum dotmaterial and a dissolving medium, dissolving and dispersing the quantumdot material in the dissolving medium and uniformly mixed to form aquantum dot paste, and applying the quantum dot paste to form a film onthe TFT layer and drying and curing to obtain the quantum dot layer. 4.The array substrate manufacturing method as claimed in claim 3, whereinin Step 2, the quantum dot material is oil soluble or water soluble; thequantum dots are in the form of spheres, bars, or fibrous forms; thedissolving medium is silica series or epoxy series; and in Step 2 thequantum dot paste is applied to the TFT layer to form the film by meansof spray coating, spin coating, printing, or slot-die coating.